Pencil



June 22, 1937. J. P. LYNN PENCIL Filed May 15, 1934 Patented June 22, 1937 PATENT OFFICE PENCIL John P. Lynn, Sycamore, Ill., assigner to Dur-O- Lite Pencil Company, Melrose Park, Ill., a corporation of Delaware Application May 15, 1934, Serial No. 725,756

Claims.

This invention relates to a mechanical pencil having a removable propelling mechanism. The present improvements are directed to certain features of construction which permit of economy in 5 manufacturing cost. More particularly my invention is concerned with the construction of a body pencil wherein is contained an axial chamber for the reception of the propelling mechanism, and one or more adjacent-chambers each adapt- 1() ed for the reception of a spare lead. The arrangement and construction is such that the several chambers maybe accommodated within a minimum of space, the body structure being producible by a mouldingoperation. Alsothe present improvements are directed to a lead propelling mechanism in which is comprised a plunger having certain peculiarities of construction which adapt it to be produced economically by a die-casting operation. The construction of such a pencil is simple in the extreme, and involves but a minimum of expense for its manufacture.

In the accompanying drawing are shown certain exemplications of this invention in the manner following:

Figure 1 is a central longitudinal section through the completed pencil;

Figs. 2 and 3 are transverse sections taken,

respectively, on lines 2-2 and 3 3 of Fig. 1; go Fig. 4 is a View in elevation of the upper end of a pencil body'in which is exhibited a modied magazine arrangement;

Fig. 5 is a similar view of a further modied arrangement of magazine chamber;

Fig. 6 is an enlarged detail in section taken on line 8 of Fig. 1;

' Fig. 7 which is a View similar to Fig. 1 shows a pencil body and propelling mechanism of slightly lmodified construction;

Fig. 8 is a view in perspective of the plunger forming part of the propelling mechanism shown in Fig. 7; and

Fig. 9 is a view in elevation of the spiral tube showing also the lower portion of the plunger in 45 operative position therewithin.

The pencil illustrated in Figure 1 comprises a body B tapered at its lower end to provide a truncated cone against'which itrtted a tip T. The body is desirably made of some such material as 50 a phenolic condensation product which is readily adaptedto moulding under heat and pressure.

In the construction shown, I have provided an axial chamber 20 extending from end to end of the body, there' being a longitudinal groove 2| 55 formed along one side of Vthe chamber which (Cl. 1Z0-18) otherwise is round. A second chamber 22 is also formed'in the body preferably diametrically opposite the groove 2|. This second chamber constitutes a magazine for holding one or more spare leads R. It need not continue through to the lower end of the body, but is desirably open at the top to permit the insertion therein of leads and Withdrawal of leads therefrom. Over the upper end of the pencil is fitted a ferrule 25 forming a head which may serve also as a support for an eraser 26. I The head furnishes a closure for both the axial chamber and the lead chamber, or as many lead chambers as may be provided.

The external configuration of the pencil is polygonal in that it is formed with a niunber of flat sides which meet at an angle. The center of each side lies a shorter distance from the pencil axis than do the angles formed at the conjuncture of these sides. I may utilize a pencil body of small diameter, yet provide Within such a body ample room for the accommodation of (l) the propelling mechanism and (2) reserve leads. In the accomplishment of this purpose, I arrange the axial and magazine chambers in close proximity and in line with a radius which extends to one of the angles at the outside of the pencilbody.-"Byso'doing it is possible to reduce the outside dimensions of the pencil to a minimum. The two chambers just referred to are furthermore so closely spaced as to render unnecessary any complete separation between them, yet I provide a constricted communicating passageway 28 which is sufliciently narrow to confine one or more reserve leads R within the chamber 22 even when the axial chamber is unoccupied.

The propelling mechanism which I have shown comprises an open spiral tube S having its lower end aflixed to the tip T and extending upwardly therefrom within the axial chamber of the body where it engages with friction sufficient to releasably hold the tube and tip in place. The lower end of the tip may be formed with cooperating jaws 3| adapted to grip between them an active lead L the extremity of which is exposed for use. To advance the lead, as required from time to time, I utilize a plunger P in the form of a cylindrical pin having a body 35 which is provided with a lateral extension 36 connecting with a head 31 which is disposed parallel to the body of the plunger. The plunger head is adapted to lie within the groove 2| wherein it is supported by the lateral extension 36 which is projected through the open spiral of the tube the upper end of which is not closed.

because the groove 2l may also be shallow inV` The plunger just described is peculiar in the respect that the lateral extension 36 is elongated in cross section as shown in Fig. 6. The long dimension of this elongated lateral extension lies obliquely of the axis of the plunger and in line with the spiral opening in the tube. Accordingly the cross sectional form of the extension is such as conform rather closely to the surfaces of the spiral opening with which the plunger cooperates. The offset head 31 is also of special cross sectional form, in that its radial dimension is relatively short. This is of advantage consequence, thereby preserving the maximum of material for the body of the pencil.

In Figs. 4 and 5, I have illustrated certain possible modications in the construction of the pencil body. In these views are shown an axial chamber having at one side thereof a shallow groove, and other deaxial chambers 43, 44 and each desirably in line with a radius which extends towards one of the'angles of the pencil exterior. These latter chambers each provide a magazine for reserve leads. To such magazine chambers are suggested in Fig. 4 and three in Fig. 5. All of the magazine chambers are in communication with the axial chamber as by a narrow constricted passageway 28, the same as has heretofore been described in connection with the structure of Fig. 3.

Referring again to Fig. 1, it will be noted that within the truncated lower end of the pencil body I have positioned a liner the .internal diameter of which about corresponds with that of the axial opening. I'his liner may be formed from a small plate bent into cylindrical form with its proximate edges separated to form a slot 5l. Extending in from its upper edge is a slot 52, the displaced material being rolled outwardly to provide an eye or hook 53. The slot 5I extending lengthwise of the liner is aligned with the rib 46 which continues on into the slot whereby in the completed pencil body the liner is anchored in place through the moulding of the material around the eye or hook 53. Inasmuch as the groove 2| extending lengthwise along the axial chamber of the pencil is in line `with the slot l5| of corresponding size in the liner, it follows that the plunger head ,31 is free to travel lengthwise of the pencil body, and out through the lower end thereof whenever required. In Figs. '7 to 9 inclusive, I have shown a generally similar construction modified to the extent of omitting deaxial magazine chambers from the body, and of utilizing a lead propelling mechanism in which the plunger P is provided at its upper end with a pair of oppositely extending fins forming a head thereof which remains always beyond the upper end of the open spiral tube S. The plunger is further provided with a radially extending projection best shown in Fig. 8 which may take the form of va tooth 56 disposed upon the side of the plunger at an oblique angle in conformity with the open spiral of the tube (see Fig. 9). This tooth is accordingly adapted to fit within the open spiral of the tube to present a long bearing therein the length of which is substantially equal to the diameter of the plunger.

In practice, it is possible to have considerable tolerance in the fit of the plunger within the spiral tube without binding -or jamming of the parts when one is moved relative to the other'. This is accounted for by reason of the long bearing furnished by the lateral projection upon the plunger which lies within the open spiral of the tube. In the case of the plunger shown in Fig. l, this long bearing is provided by the elongated form of the lateral extension 36, and in the plunger of Fig. 8 it is furnished by the elongated tooth 5B. It is found in operation that the plunger may occupy a deaxial position within lthe tube without binding of the parts such as commonly occurs in the case of a lateral projection having a single point or relatively short bearing.

The plunger constructed as herein described has the advantage of minimum cost withal dependability in operation. The lateral projecting parts of such a plunger are formed not by displacing material from some other portion of the plunger, thereby conducing to weakness thereof, but by adding on material, as needed, to form such projecting parts. A11 this takes place in the single casting operation required for the production of the plunger, thereby conducing to a ready andoperative t of plunger within the axial tube.

I claim:

1. In a pencil, the combination of a body containing lead-propelling mechanism comprising an open spiral tube and a plunger slidably disposed within the spiral tube, the plunger having a body formed with a single radially extending part, said part extending substantially onehalf of the circumference of the plunger without reducing the cross-sectionalY area of the plunger at any point with its long dimension disposed obliquely to the axis of the plunger and in line with the spiral openings of the tube wherein such radially extended part is adapted to lie, and a longitudinally extending head wholly beyond the spiralV tube for holding said radially extending part against twisting and binding within the spiral openings of the tube.

2. In a pencil, the combination of a body, and relatively movable lead advancing mechanism including a cylindrical plunger, a single threadlike portion projecting from one side of said plunger and extending over substantially onehalf the circumference thereof, said projecting portion having oppositely curved upper and lower surfaces, and said portion being of substantially greater transverse width Vthan the diameter of `sai-d plunger.

Y 3. vIn a pencil, the combination of a body, lead advancing mechanism including a plunger having ahead and a radially extending, transversely elongated projection at one side of said plunger, said projection extending over only substantially one-half of the circumference of said plunger with its upper and lower surfaces disposed obliquely to the axis of the plunger and without reducing the diameter of the plunger at any point.

4. A pencil plunger consisting of a body and a thread projection formed thereon, extending over only substantially one half of the circumference of the body, said projection being formed outside of the body without reducing the cross sectional area of the body at any point, and constituting the sole projection beyond the periphery of the body.

5. A pencil plunger consisting of a bodyV and a projection thereon having the function of a thread, said projection extending over only substantially one half of the circumference of the body, and being formed outside of the body diameter without reducing said diameter at any point, and constituting-the sole projection beyond the periphery of the body. Y

6. A pencil plunger consisting of a body and a thread projection formed thereon, extending over only substantially one half of the circumference of the body,said projection being formed outside of the body Without reducing the cross sectional area of the body at any point, said half thread presenting relatively square shoulders at its terminal points, and constituting the sole projection beyond the periphery of the body.

7. In a pencil, the combination of a body containing lead-advancing mechanism including, a plunger consisting of a body having a radially extending projection adjacent one end and functioning as a thread, ahead carried at the outer end of said projection, and said projection being disposed obliquely to the axis of the plunger for substantially one-half of the circumference thereof without reducing the cross-sectional area of the plunger at any point, and constituting the sole said projection beyond the periphery of the body.

8. In a pencil having a body containing a spirally formed lead-holding tube, a lead-advancing plunger adapted to be operated through said tube, and comprising a body having a thread-like projection formed adjacent one end of the body to extend over substantially one-half the circumference of the body, said projection being formed outside the body without reducing the cross-sectional area of the body at any point and having its opposite sides slanted in conformity with the pitch of the spiral Walls of the tube.

9. In a pencil having a body containing a spirally formed lead-holding tube, a lead-advancing plunger adapted to be operated through said tube, and comprising a body having a thread-like projection formed adjacent one end of the body to extend over substantially one-half the circumference of the body, said projection being formed outside the body Without reducing the cross-sectional area of the body at any point and having its opposite sides slanted in conformity with the pitch of the spiral Walls of the tube, and a guiding head carried by the outer end of said projection.

10. A pencil plunger consisting of a body and a pitched thread projection formed at one end thereof, extending over only substantially onehalf of the circumference of the body, said projection being formed outside of the body Without reducing the cross-sectional area of the body at any point, and constituting the sole projection beyond the periphery of the body.

JOHN P. LYNN. 

